The present invention generally relates to a pressure applying device for use in an image forming apparatus or the like and more particularly, to a pressure applying device for fixing rollers which are adapted to fix toner particles onto a record sheet through application of pressure to the toner particles in the image forming apparatus.
Toner particles or the like mainly composed of resin are generally employed as a developer material in an image forming apparatus. The toner particles are carried onto an eletrostatic latent image formed on the surface of a photosensitive member in the developing station of the image forming apparatus and are subsequently transferred onto a record sheet at the transfer station. Thereafter, the toner particles are fixed at a fixing station in the image forming apparatus with a pair of fixing rollers having been widely employed as the fixing devices, which rollers function to fix the toner particles onto the record sheet through the application of heat and pressure. In such a fixing device, a pressure applying device is provided in addition to the fixing rollers to bring the upper and lower rollers into appropriate pressure contact with each other. Conventionally, the pair of fixing rollers have been held in pressure contact with each other mechanically by a lever provided outside of the image forming apparatus. The pressure applying device of the above described type has, however, some disadvantages, such that the device has been necessarily complicated in construction and formed undesirably large in size.